Eczema in a young baby can be a sign that the child will develop more allergies.
A new study published Tuesday in the journal Pediatrics confirms a phenomenon known as the “allergic march,” a pattern that explains trends in the onset and progression of allergies in children from infancy to age three.
The study analyzed medical record data collected from more than 200,000 children between 1999 and 2020 and found that children tend to be first diagnosed with eczema, also known as atopic dermatitis, at an average age of 4 months. A diagnosis of symptomatic food allergy was then made. From hives Anaphylaxis (a life-threatening allergic reaction that can affect the whole body and cause swelling or blockage of airways) and asthma, both around 13 months of age. The study found that children developed allergic rhinitis, or hay fever, at 26 months of age. Rarely, a child can develop her fifth allergy, called eosinophilic esophagitis, by the age of 35 months.
The “allergy march” does not mean that all children with eczema will develop all the allergies listed, said Dr. Stanislaw Gavryshewski of the Department of Allergy and Immunology at Children’s Hospital of Philadelphia, who led the study.
“Every child is different. Some may have one, some may have two, some may have all,” he said.
About 1 in 5 children have these types of allergies, making them one of the most common chronic diseases in children. Researchers say just over 13% of children have at least two types of allergy symptoms.
The results of this study will help both parents and doctors to monitor children who develop eczema at an early age more closely for other allergies later in life.
“Eczema early in life is the greatest risk factor for developing allergies later in life than family history,” said Ruchi Gupta, Ph.D., founding director of the Center for Food Allergy and Asthma Research at Northwestern University and Lurie Children’s Hospital in Chicago, who was not involved in the study.
The medical community has long recognized the allergic march, but this study is the largest study to confirm the pattern. Also, while previous studies focused primarily on white children, about a third of the children in this study were black. About 10% were Hispanic and a smaller percentage (3% or less) were Asian or Pacific Islander.
“This study adds new evidence that a child can have multiple allergic diseases because allergic diseases can begin early in life and progress in allergic disease can occur simultaneously,” said Dr. Sharon Chintraja, an immunologist at Stanford University School of Medicine, who was not involved in the study.
For example, the initial allergy symptoms may subside, leaving the child with only food allergies, but allergies may accumulate and the child may have multiple types of allergies, she added. For some people, certain allergies can come and go, Chintraja said.
Food allergies are not as common as previous studies have found, affecting about 4% of the children studied, about half the rate seen in studies that self-report allergies. The most common food allergies were peanuts, eggs, and shellfish. Patients with respiratory allergies such as asthma and allergic rhinitis usually had both of these symptoms in addition to other allergic symptoms.
The study also found that eosinophilic esophagitis, a rare type of food allergy that causes inflammation in the esophagus, affects more nonwhite children than previously thought. Approximately 40% of children with this condition were not Caucasian. Overall, this allergy was very rare, occurring in only 0.1% of children.
A better understanding of how allergies generally develop may lead to treatments that can halt their progression or stop them from developing altogether.
If you can prevent eczema, “can you also prevent food allergies, environmental allergies, and asthma?” Gupta asked. “We don’t know yet, but research is being done.”
Chintraja also agreed.
“Our job as researchers is to identify how to intervene early and how those interventions affect many, not just one, of the five allergic diseases,” she said.
That research will need to elucidate the relationship between genetics and environmental factors, such as climate change, that exacerbate seasonal allergies.
“Ultimately, the interaction of the two will determine which children develop allergies and, if they do, how severe they are,” Gavryshevsky said.
